| dc.description.abstract | Four experiments involving 104 pigs were conducted to study different
aspects of manganese (Mn) nutrition in swine.
In the first experiment, a basal diet (16.2 ppm Mn) and basal
diet supplemented with 10 ppm of Mn from MnS04·H20, HnCO) or MnO uere
compared for Mn availability to.the growing pig. Growth .rates were equal on all diets. Mn availability as measured by Mn balance data and
tissue Mn concentrations indicated that Mn from the supplemented diets
was more available than that from the basal diet. Mn retention, as a
percent of intake, was higher on M" from the supplemented diets than
the basal diet. Regardless of dietary Mn source, over 90% of excreted
Mn was recovered in the feces. Within the supplemented diets, Mn was
essentially equally available to the growing pig. Hemoglobin, hematocrit,
serum Mn and serum alkaline phosphatase did not differ significantly
due to dietary treatment.
In the second experiment, flux patterns across the wall of the
gastrointestine of Mn from different sources was studied. Net absorption
of Mn from the basal diet was evident in two sections of the gut;
the stomach and the cecum, whereas Mn from the supplemented diets was
apparently absorbed in the stomach, cranial small intestine and cecum.
The net cecal absorption,of Mn from the basal diet was higher than that
of Mn from the supplemented diets. Net Mn secretion in the caudal
small intestine and the rectum was much higher on the supplemented than
on the basal diet, but this trend was reversed in the colon. The pH
values of the gut contents from different sections of the tract were
not significantly different between dietary treatments.
In the third experiment, two ratios of Ca to P, two levels of Ca
and P and two levels of Mn were studied using a factorial feeding trial.
Mn supplementation significantly increased heart Mn levels and significantly
depressed rib Ca and Mg values. Mn supplementation did not
affect serum Ca, inorganic P, Mg and alkaline phosphatase levels.
Dietary Mn levels had no significant effect on rib and metacarpal
physical measurements, breaking strength and related parameters. A
2 to I Ca to P ratio significantly (P<0.05) depressed rib Mn content.
The increased levels of Ca and P supplementation significantly (P<0.01)
increased rib, pancreas and serum Mn levels but significantly (P<0.01)
depressed metacarpal Mn concentration. There was a significant (P<0.05
to P<0.05) interaction between levels of Ca and P and ratios of Ca to
P on the levels of serum, liver and pancreas Mn, and on metacarpal Mn
values. High levels of Ca and P in both ratios had a depressing effect
on metacarpal Mn concentration. Feeding Mn along with Ca and P, in a
2 to I ratio, increased liver Mn. Metacarpal Mg was depressed when Ca
and P were given in a I to 2 ratio.
The interaction between Ca and P levels and Mn levels was significant
(P<0.05) with respect to rib ash content, Ca and P, metacarpal Mn
and serum inorganic P. With lower Ca and P levels, Mn supplementation
increased metacarpal Mn and serum inorganic P but depressed rib ash, Ca
and P concentration. The significant effects of Mn supplementation on
rib Mg, metacarpal internal vertical diameter and heart and serum Mn
u~8appeared when Ca and P supplements were also fed. The 3-way
interaction between level of Ca and P, ratio of Ca to P and level of
Mn was significant (P<0.05) relative to rib and serum Mn levels,
pancreas dry matter and metacarpal Mg content and elasticity. With
high or low Ca and P levels in a 2 to 1 ratio, Mn supplementation
increased rib and serum Mn and pancreas dry matter but depressed metacarpal
elasticity. With low Ca and P levels in a 1 to 2 ratio, Mn
supplementation increased serum and metacarpal Mn, but high Ca and P
levels in the same ratio depressed rib and serum Mn, metacarpal Mg
and pancreas dry matter and increased metacarpal elasticity.
Mn supplementation produced more nearly normal histologic structure
of the epiphysis than the basal diet, but animals on high Mn
levels had significantly (P<0.05) less compact bone in the diaphysis.
However, the thickness of the epiphyseal cartilagenous plate was not
affected. There was a significant (P<0.05) interaction between Ca to
P ratio and Mn level on the histology of the epiphysis. The interaction
of diet Mn with Ca and P levels was significant (P<0.05) in relation to
the thickness of the epiphyseal cartilagenous plate. These changes
were not typical of rickets but were changes in which there was failure
of production of compact bone in the region of the diaphysis. However,
the deleterious effects on weight gain, feed efficiency and histology
of bone of a low dietary P level (0.35%) from soybean meal were much
more pronounced than the effects of excessive dietary levels of Ca and
P or of an inverse Ca to P ratio, regardless of dietary Mn supplementation.
In the fourth experiment, the Mn requirements of the baby pig born
of sows fed a low Mn diet were determined using three dietary Mn concentrations.
Growth, Mn balance data and serum Mn concentration were used
as measures of sufficiency. Average daily gain, serum Mn, Mn retention,
fecal Mn excretion and urinary Mn excretion as percent of intake were
significantly (P<0.01 or P<0.05) different between dietary treatments.
The average daily gain and feed efficiency were highest on 2.67 ppm Mn
in the diet. Mn intake was highly correlated with serum Mn and serum
alkaline phosphatase activity but not with average daily gain and feed
efficiency. Mn retention as percent of intake had very high negative
correlations with feed efficiency and urinary Mn excretion as percent
of intake. Fecal and urinary Mn excretion as percent of intake was
significantly higher on the basal diet (0.46 ppm Mn). There was a
negative Mn retention on this diet. Serum Mg levels substantially
declined in pigs on the basal diet 28 days after the start of the
experiment. Average daily gain was positively related to Mn retention
as percent of intake and negatively related to fecal Mn excretion as
.percent of intake. Mn retention and fecal Mn excretion, both as percent
of intake, were much more highly correlated with growth rate than
absolute Mn intake, excretion and retention and the serum parameters
examined.
Based on all criteria examined, the dietary Mn requirements of the
baby pig on a semipurified diet are probably between 3 and 6 ppm. | en |
